Re: high load with usb device

[Avi Kivity <avi@redhat.com>]

  On 09/14/2010 12:25 PM, Michael Tokarev wrote:
> Not that it is much helpful either.  lsof:
>
> qemu-syst 23203  mjt    0u   CHR   136,9      0t0      12 /dev/pts/9
> qemu-syst 23203  mjt    1u   CHR   136,9      0t0      12 /dev/pts/9
> qemu-syst 23203  mjt    2u   CHR   136,9      0t0      12 /dev/pts/9
> qemu-syst 23203  mjt    3u   CHR  10,232      0t0    4402 /dev/kvm
> qemu-syst 23203  mjt    4u  0000     0,9        0     607 anon_inode
> qemu-syst 23203  mjt    5r  FIFO     0,8      0t0 8172675 pipe
> qemu-syst 23203  mjt    6w  FIFO     0,8      0t0 8172675 pipe
> qemu-syst 23203  mjt    7u   CHR  10,200      0t0    1228 /dev/net/tun
> qemu-syst 23203  mjt    8u  0000     0,9        0     607 anon_inode
> qemu-syst 23203  mjt    9u  IPv4 8173217      0t0     TCP *:5900 (LISTEN)
> qemu-syst 23203  mjt   10u  0000     0,9        0     607 anon_inode
> qemu-syst 23203  mjt   11u  0000     0,9        0     607 anon_inode
> qemu-syst 23203  mjt   12u  0000     0,9        0     607 anon_inode

> So it is constantly poking fds# 11, 12, 10, 5&  6.
> 5 and 6 are pipe (selfpipe?),

signalfd emulation, used to deliver signals efficiently.  Older glibc?

> and 10..12 are "anon inode".

Those are likely eventfds.

> Here's the command line again:
>
> qemu-system-x86_64 \
>    -netdev type=tap,ifname=tap-kvm,id=x \
>    -device virtio-net-pci,netdev=x \
>    -monitor stdio \
>    -boot n \
>    -usbdevice tablet \
>    -m 1G \
>    -vnc :0
>
> Yes, it does quite a lot of timer stuff... ;)
>
>

So timers internal to usb.

Please try (independently):

- just -usb, without -usbdevice tablet
- instrument calls to qemu_mod_timer() in hw/usb-*hci.c.  Looks like 
these are all 1kHz, but something else is clearly happening.

-- 
error compiling committee.c: too many arguments to function